Great Rock Mine is a disused mica

Mica

The mica group of sheet silicate minerals includes several closely related materials having highly perfect basal cleavage. All are monoclinic, with a tendency towards pseudohexagonal crystals, and are similar in chemical composition...

ceous haematite mine

Mining

Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 about 3 km north of the town of Bovey Tracey

Bovey Tracey

Bovey Tracey is a small town in Devon, England, on the edge of Dartmoor, its proximity to which gives rise to the "slogan" used on the town's boundary signs, "The Gateway to the Moor". The locals just call the town "Bovey" ....

 in Devon

Devon

Devon is a large county in southwestern England. The county is sometimes referred to as Devonshire, although the term is rarely used inside the county itself as the county has never been officially "shired", it often indicates a traditional or historical context.The county shares borders with...

, England

England

England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...

. It was worked from the 19th century until 1969, and was the last active mine in the Dartmoor National Park area.

At its most active during the 1940s, the mine produced 2,500 ton

Ton

The ton is a unit of measure. It has a long history and has acquired a number of meanings and uses over the years. It is used principally as a unit of weight, and as a unit of volume. It can also be used as a measure of energy, for truck classification, or as a colloquial term.It is derived from...

s of micaceous haematite per year. The mineral was an important ingredient in the rust

Rust

Rust is a general term for a series of iron oxides. In colloquial usage, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture...

-resistant paint

Paint

Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...

 used on Royal Navy

Royal Navy

The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...

 ships and on bridges, including the Royal Albert Bridge

Royal Albert Bridge

The Royal Albert Bridge is a railway bridge that spans the River Tamar in the United Kingdom between Plymouth, on the Devon bank, and Saltash on the Cornish bank. Its unique design consists of two lenticular iron trusses above the water, with conventional plate-girder approach spans. This gives...

 and the Sydney Harbour Bridge

Sydney Harbour Bridge

The Sydney Harbour Bridge is a steel through arch bridge across Sydney Harbour that carries rail, vehicular, bicycle and pedestrian traffic between the Sydney central business district and the North Shore. The dramatic view of the bridge, the harbour, and the nearby Sydney Opera House is an iconic...

.